Thanks, that all makes it a little less concerning.
FWIW, This is a Denon DP-300F, no ground wire. I added a Grado Red MM cartridge.
The receiver does not have a MM/MC switch.
The NAD is just a little box. It does have dedicated MM & MC inputs and a switch, plus a ground. But there is no type of control that I can see to vary output levels on it.
BTW, what would I attach the ground wire too?? The rack is metal and glass -- would one wrap it onto a bare-metal area of the rack?
Either way, the M3s sound great with the Yamaha -- vinyl especially sweet of course ...